Issue link: https://iconnect007.uberflip.com/i/1470111
18 DESIGN007 MAGAZINE I JUNE 2022 rule. We should talk about how to improve these documents. Many companies have a secondary speci- fication which says, "We also want you to do the following items," such as, "e PCB shall be RoHS compliant. We require IPC Class three via plating requirements, but Class two with everything else, etc." I've put together a generic version of that secondary acceptance specification. I'm offering that document to the industry to provide more detailed infor- mation for companies that don't have this. is specification, along with appropriate IPC specifications, should be able to provide enough information so someone could design a perfect board without any issues being noted by the manufacturer. e industry has the IPC-2581 data format which is not perfect, but close. Get the specifi- cations into soware. Let's get the design rules out there. Maybe we'll have a better shot at doing this right. I don't know. It's just another attempt to try something, right? Feinberg: Well, that would eliminate the design- ing in a vacuum. If you had an IPC class A set of design rules, which is 95% of the industry can build this with high yield and high reliability or something, and then you had design rules B, and design rules C and D as you went up, the design rules became tighter. You had some kind of test vehicle to see that a company could build to see if they meet the criteria of these higher ones. en to be safe, well, we're always going to default to IPC design rules A. At least you can tell that this is a B, C, or a D, or some- thing like that. If you don't answer all the ques- tions, we'll default to that. Korf: Yes. I usually give them, "Here's a stan- dard in advance." In my DFM class, I actually give these documents to the students, and I say, "It's an open PDF file. I want you to send it to your vendors and have them fill out the columns. Have them edit it for you and send it back to you." If you tell them, "I want all the rules," they don't have enough time to write them all down. But if you send this, instead of starting with a white piece of paper, you start with something and edit it. You'll get some- thing back faster. Feinberg: Has anyone tried that? Korf: I haven't heard back yet. I've heard back from a couple who have gotten some pushback from the suppliers. Feinberg: It would be really interesting as a fol- low-up to find out if anyone has done that and gotten any response, and what the response was. Korf: Actually, I'll agree. Let's go out and query all the students and see if these made any dif- ference. Did the class make any difference? It's the same with brand-new PCB designers. What's the first documentation or training they need to start laying boards out? Well, we should have these sets of design rules in their face. At least they have something rather than a bunch of yellow sticky notes around the moni- tor, right? Shaughnessy: Right. Dana, was there anything else you wanted to mention? Korf: Well, if we're talking about DWM, what do we call what we're currently doing—design- ing without manufacturing, or DWOM? Shaughnessy: I assume! (laughs) Korf: We have to stop assuming. (laughs) Shaughnessy: anks for your time, Dana. is has been really good. Korf: ank you. It's been great, guys. DESIGN007 Dana Korf is the principal consultant at Korf Consultancy LLC, and an I-Connect007 columnist. To read past columns or contact Korf, click here.